Daily, prospective associations between sleep architecture and affect: insights from Bayesian multilevel compositional data analysis.

Background: Emerging statistical methods addressing the multilevel compositional nature of sleep architecture can offer insights into how daily time reallocations between sleep stages (total wake time in bed [TWT], light sleep [Non rapid eye movement stage 1 and 2], slow wave sleep [SWS], and rapid eye movement [REM] sleep) are associated with post-sleep affect.

Purpose: This study investigated the daily, prospective association between sleep architecture and affect.

Methods: In 96 healthy, young adults across 15 consecutive days, sleep architecture was measured at night using electroencephalography (Z-Machine Insight+) and affect was self-reported using the PANAS-X at awakening. Bayesian multilevel compositional data analysis examined how reallocating time between sleep stages was associated with affect.

Results: Various reallocations of sleep stages predicted affect, at both within- and between-person levels. Between-person reallocation of 30 min/night from light or REM sleep to SWS was associated with ≥0.38 points higher high and low arousal positive affect, and from SWS to any other sleep stages was associated with ≥0.21 points higher high arousal negative affect. Within-person reallocation of 30 min/night from REM to any other stages predicted ≥0.05 points higher high arousal negative affect, and 30 min/night from TWT to SWS or REM predicted ≤-0.07 lower low arousal negative affect.

Conclusions: Findings highlight the distinct constellations of sleep architecture associated with affect in everyday life. Extension of SWS and REM for improving affect, while considering other off-set sleep stages, should be confirmed in experimental research in daily settings, to inform diagnostic and intervention strategies for sleep and affective disorders.